[fix](pipelineX) fix do not set per_fragment_instance_idx

[Mryange]

Proposed changes

add case to test pipelineX union

Further comments

If this is a relatively large or complex change, kick off the discussion at dev@doris.apache.org by explaining why you chose the solution you did and what alternatives you considered, etc...

[Mryange]

run buildall

[github-actions]

clang-tidy review says "All clean, LGTM! 👍"

[doris-robot]

TeamCity be ut coverage result:
Function Coverage: 36.33% (8115/22338)
Line Coverage: 28.44% (64907/228251)
Region Coverage: 27.33% (33670/123214)
Branch Coverage: 23.98% (17184/71662)
Coverage Report: http://coverage.selectdb-in.cc/coverage/db84bda9740859cbeb84823dbc70c448ecff7959_db84bda9740859cbeb84823dbc70c448ecff7959/report/index.html

[Mryange]

run buildall

[github-actions]

clang-tidy review says "All clean, LGTM! 👍"

[doris-robot]

TeamCity be ut coverage result:
Function Coverage: 36.33% (8115/22338)
Line Coverage: 28.43% (64900/228251)
Region Coverage: 27.32% (33667/123214)
Branch Coverage: 23.98% (17183/71662)
Coverage Report: http://coverage.selectdb-in.cc/coverage/8e495d9a0515329f490c0da8bdf080180bea96c2_8e495d9a0515329f490c0da8bdf080180bea96c2/report/index.html

[doris-robot]

(From new machine)TeamCity pipeline, clickbench performance test result:
the sum of best hot time: 45.72 seconds
stream load tsv: 577 seconds loaded 74807831229 Bytes, about 123 MB/s
stream load json: 20 seconds loaded 2358488459 Bytes, about 112 MB/s
stream load orc: 64 seconds loaded 1101869774 Bytes, about 16 MB/s
stream load parquet: 31 seconds loaded 861443392 Bytes, about 26 MB/s
insert into select: 28.4 seconds inserted 10000000 Rows, about 352K ops/s
storage size: 17162359419 Bytes

[Gabriel39]

LGTM

[github-actions]

PR approved by at least one committer and no changes requested.

[github-actions]

PR approved by anyone and no changes requested.